code: def testExtractChords(self):
      music_testing_lib.add_chords_to_sequence(
          self.note_sequence, [("C", 2), ("G7", 6), ("F", 8)]
      )
      quantized_sequence = sequences_lib.quantize_note_sequence(
          self.note_sequence, self.steps_per_quarter
      )
      quantized_sequence.total_quantized_steps = 10
      chord_progressions, _ = chord_pipelines.extract_chords(
          quantized_sequence
      )
      expected = [
          [NO_CHORD, NO_CHORD, "C", "C", "C", "C", "G7", "G7", "F", "F"]
      ]
      self.assertEqual(
          expected, [list(chords) for chords in chord_progressions]
      )
  
file_path: magenta/magenta/pipelines/chord_pipelines_test.py
imports: from absl.testing import absltest
  from magenta.common import testing_lib
  from magenta.pipelines import chord_pipelines
  from magenta.pipelines import melody_pipelines
  from note_seq import chords_lib
  from note_seq import constants
  from note_seq import sequences_lib
  from note_seq import testing_lib
  from note_seq.protobuf import music_pb2
label_desc: Use image node_id 4 for calling the ChordPipelinesTest obj's underlying member method code with example usage: obj.testExtractChords() without return types